Thermostable DNA polymerase from anaerocellum thermophilum

ABSTRACT

A thermostable enzyme is provided which is derived from the microorganism Anaerocellum thermophilum&lt;l&gt;. The enzyme has a molecular weight of 96 to 100 kDa, shows DNA polymerase activity and reverse transcriptase activity in the presence of magnesium ions. The enzyme may be native or recombinant, and may be used with selected primers and nucleoside triphosphates in a temperature cycling polymerase chain reaction on DNA or RNA as template with or without additional DNA polymerases as an enzyme mixture.

The present invention relates to a thermostable enzyme which is a DNA polymerase obtainable from Anaerocellum thermophilum.

Heat stable DNA polymerases (EC 2.7.7.7. DNA nucleotidyltransferase, DNA-directed) have been isolated from numerous thermophilic organisms (for example: Kaledin et al., 1980, Biokimiya Vol. 45, p. 644-651; Kaledin et al., 1981, Biokimiya Vol. 46, p. 1247-1254; Kaledin et al.,1982, Biokimiya Vol. 47, p. 1515-1521; Ruttimann, et al., 1985, Eur. J. Biochem. Vol. 149, p. 41-46; Neuner et al., 1990, Arch. Microbiol. Vol. 153, p. 205-207.)

For some organisms, the polymerase gene has been cloned and expressed (Lawyer et al., 1989, J. Biol. Chem. Vol. 264, p. 6427-6437; Engelke et al., 1990, Anal. Biochem. Vol. 191, p. 396-400; Lundberg et al., 1991, Gene, Vol. 108, p. 1-6; Kaledin et al., 1980 Biokimiya Vol. 44, p. 644-651; Kaledin et al., 1981, Biokimiya Vol. 46, p. 1247-1254; Kaledin et al., 1982, Biokimiya Vol. 47, p. 1515-1521; Ruttimann, et al., 1985, Eur. J. Biochem. Vol. 149, p. 41-46; Neuner et al., 1990, Arch. Microbiol. Vol. 153, p. 205-207; Perler et al., 1992, Proc. Natl. Acad. Sci. USA Vol. 89, p. 5577).

Thermophilic DNA polymerases are increasingly becoming important tools for use in molecular biology and there is growing interest in finding new polymerases which have more suitable properties and activities for use in diagnostic detection of RNA and DNA, gene cloning and DNA sequencing. At present, the thermophilic DNA polymerases mostly used for these purposes are from Thermus species like Taq polymerase from T. aquaticus (Brock et al 1969, J. Bacteriol. Vol. 98, p. 289-297).

Reverse transcription is commonly performed with viral reverse transcriptases like the enzymes isolated from Avian myeloblastosis virus or Moloney murine leukemia virus, which are active in the presence of Magnesium ions but have the disadvantages to possess RNase H-activity, which destroys the template RNA during the reverse transcription reaction and have a temperature optimum at 42° C. or 37° C., respectively.

Alternative methods are described using the reverse transcriptase activity of DNA polymerases of thermophilic organisms which are active at higher temperatures. Reverse transcription at higher temperatures is of advantage to overcome secondary structures of the RNA template which could result in premature termination of products. Thermostable DNA polymerases with reverse transcriptase activities are commonly isolated from Thermus species. These DNA polymerases however, show reverse transcriptase activity only in the presence of Manganese ions. These reaction conditions are suboptimal, because the presence of Manganese ions lowers the fidelity of the DNA polymerase transcribing the template RNA.

Therefore, it is desirable to develop a reverse transcriptase which acts at higher temperatures to overcome secondary structures of the template and is active in the presence of Magnesium ions in order to prepare cDNA from RNA templates with higher fidelity.

The present invention addresses these needs and provides a purified DNA polymerase enzyme (EC 2.7.7.7.) active at higher temperatures which has reverse transcriptase activity in the presence of magnesium ions. The invention comprises a DNA polymerase isolated from Anaerocellum thermophilum DSM 8995, deposited on the Deutsche Samnulung von Mikro-organismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig. In a further aspect the invention comprises a DNA polymerase that catalyses the template directed polymerisation of DNA and posess 5′-3′-polymerase activity, 5′-3′-exonuclease activity and no substantial 3′-5′-exonuclease activity.

The polymerase according to the present invention retains at least 90% of its activity after incubation for 30 Minutes at 80° C. in absence of stablilizing detergents.

In a further aspect the invention comprises a DNA polymerase having a molecular mass of about 96 to 100 kDa as determined by in situ activity PAGE analysis.

In a futther aspect the invention comprises a DNA a polymerase having reverse transcriptase activity in the presence of magnesiums ions and in the substantial absence of maganese ions. The polymerase according to the present invention exhibits a Mg²⁺ dependent reverse transcriptase activity of more than 30% relative to the DNA polymerase activity which is set to 100%. In further aspect the present invention comprises a thermostable DAN polymerase wherein said polymerase exhibits a reverse transcriptaqse activity which is Mn²⁺ dependent. The Mn²⁺ dependent reverse transcriptase activity is more than 60% relative to the DNA polymerase activity.

In further aspect the invention comprises a thermostable reverse transcriptase. The thermostable reverse transcriptase retains more than 80% after incubation for 60 minutes at 80° C.

Moreover, DNA encoding the 96.000-100.000 daltons thermostable DNA polymerase obtainable from Anearocellum thermophilum has been isolated and which allows to obtain the thermostable enzyme of the present invention by expression in E. coli. the entire Anearocellum thermophilum DNA polymerase coding sequence is depicted below as SEQ ID NO. 7. The recombinant Anearocellum thermophilum DNA polymerase also possesses 5′-3′polymerase activity, no substantial 3′-5′-exonuclease activity, 5′-3′-exonuclease activity and a reverse transcriptase activity which is a Mg²⁺ dependent.

Anaerocullum thermophilum was isolated from a hot spring in the Valley of Geyser in Kamchatka (V. svetlichny et al. Mikrobilogiya, Vol. 59, No. 5 p. 871-879, 1990). Anaerocullum thermophilum was deposited with the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig under the terms of the Budapest Treaty and received DSM Accession Number 8995. The thermostable polymerase isolated from Anaerocellum thermophilum has a molecular weight of 96 to 100 kDa and retains more than 90% of activity after heating to 80° C. for 30 minutes in absence of stabilizing detergents. The thermostable enzyme possesses a 5′-3′ polymerase activity and a reverse transcriptase activity which is Mn⁺⁺ as well as Mg⁺⁺-dependent. The thermostable enzyme may be native or recombinant and may be used for first and second strand cDNA synthesis, in cDNA cloning, DNA sequencing, DNA labeling and DNA amplification.

The present invention provides improved methods for the replication and amplification of deoxyribonucleic (DNA) and ribonucleic acid (RNA) sequences. These improvements are achieved by the discovery and application of previously unknown properties of thermoactive DNA polymerases. In a preferred embodiment, the invention provides a method for synthesizing a complementary DNA copy from an RNA template with a thermoreactive DNA polymerase. In another aspect, the invention provides methods for amplifying a DNA segment from an RNA or DNA template using a thermostable DNA polymerase (RT-PCR or PCR).

The term “reverse transcriptase” describes a class of polymerases characterized as RNA-dependent DNA polymerases. All known reverse transcriptases require a primer to synthesize a DNA transcript from an RNA template. Historically, reverse transcriptase has been used primarily to transcribe mRNA into cDNA which can then be cloned into a vector for further manipulation.

For recovering the native protein Anaerocellum thermophilum may be grown using any suitable technique, such as the technique described by Svetlichny et al., 1991, System. Appl. Microbiol. Vol. 14, p. 205-208. After cell growth one preferred method for isolation and purification of the enzyme is accomplished using the multi-step process as follows:

The cells are thawed, suspended in buffer A (40 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7 mM 2-mercaptoethanol, 0.4 M NaCl, 10 mM Pefabloc™ SC (4-(2-Aminoethyl)-benzolsulfonyl-fluorid, Hydrochlorid) and lysed by twofold passage through a Gaulin homogenizer. The raw extract is cleared by centrifugation, the supernatant dialyzed against buffer B (40 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7 mM 2-mercaptoethanol, 10% Glycerol) and applied onto a column filled with Heparin-Sepharose (Pharmacia). In each case the columns are equilibrated with the starting solvent and after application of the sample the columns are washed with the threefold of their volume with this solvent. Eluation of the first column is performed with a linear gradient of 0 to 0.5 M NaCl in Buffer B. The fractions showing polymerase activity are pooled and ammonium sulfate is added to a final concentration of 20%. This solution is applied to a hydrophobic column containing Butyl-TSK-Toyopearl (TosoHaas). This column is eluted with a falling gradient of 20 to 0% ammonium sulfate. The pool containing the activity is dialyzed and again transferred to a column of DEAE-Sepharose (Pharmacia) and eluted with a linear gradient of 0-0.5 M NaCl in buffer B. The fourth column contains Tris-Acryl-Blue (Biosepra) and is eluted as in the preceding case. Finally the active fractions are dialyzed against buffer C (20 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7.0 mM 2-mercaptoethanol, 100 mM NaCl, 50% Glycerol).

DNA polymerase activity was either measured by incorporation of ³²P-dCTP or by incorporation of digoxigenin labeled dUTP into the synthesized DNA. Detection and quantification of the incorporated digoxigenin was performed essentially as described in Holtke, H.-J.; Sagner, G. Kessler, C. and Schmitz, G., 1992, Biotechniques Vol. 12, p. 104 -113.

Reverse transcriptase activity was measured using oligo dT primed poly A template by incorporation of either ³²P-dTTP or digoxigenin-labeled dUTP into the complementary strand. Detection of the incorporated digoxigenin was performed in analogy to the procedure used for detection of DNA polymerase activity.

In situ PAGE analysis of polymerase activity and reverse transcriptase activity was performed essentially according to the method described by Spauos A. and Hübscher U., 1983, Methods in Enzymology Vol. 91 p. 263-277. Some minor, but essential modifications to the original method are, that the renaturation of the SDS-denatured polypeptides is performed in the presence of magnesium ions (3 mM) and dATP (0.5-1 μM) to assist refolding.

The thermostable enzyme of this invention may also be produced by recombinant DNA techniques, as the gene encoding this enzyme has been cloned from Anaerocellum thermophilum genomic DNA. In a firer aspect the invention includes a recombinant plasmid comprising the vector pASK75 carrying the Anaerocellum thermophilum DNA polymerase gene and designated pAR10.

The isolation of the recombinant clone expressing DNA polymerase from Anaerocellum thermophilum includes the following steps: chromosomal DNA from Anaerocellum thermophilum is isolated by treating the cells with detergent e.g. SDS and a proteinase e.g. Proteinase K. The solution is extracted with phenol and chloroform and the DNA purified by precipitation with ethanol. The DNA is dissolved in Tris/EDTA buffer and the gene encoding the DNA polymerase is specifically amplified by the PCR technique using two mixed oligonucleotides (primer 1 and 2). These oligonucleotides, described in SEQ ID NO.: 1 and SPQ ID NO.: 2, were designed on the basis of conserved regions of family A DNA polymerases as published by Braithwaite D. K. and Ito J., 1993, Nucl. Acids Res. Vol. 21, p. 787-802. The specifically amplified fragment is ligated into an vector, preferably the pCR™II vector (Invitrogen) and the sequence is determined by cycle-sequencing. Complete isolation of the coding region and the flanking sequences of the DNA polymerase gene can be performed by restriction fragmentation of the Anaerocellum thermophilum DNA with another restriction enzyme as in the first round of screening and by inverse PCR (Innis et al., (1990) PCR Protocols; Academic Press, Inc., p. 219-227). This can be accomplished with synthesized oligonucleotide primers binding at the outer DNA sequences of the gene part but in opposite orientation. These oligonucleotides, described by SEQ ID Nos. 3 and 4, were designed on the basis of the sequences which were determined by the first above described PCR. As template Anaerocellum thermophilum DNA is used which is cleaved by restriction digestion and circularized by contacting with T4 DNA ligase. To isolate the coding region of the whole polymerase gene, another PCR is performed using primers as shown in SEQ ID Nos. 5 and 6 to amplify the complete DNA polymerase gene directly from genomic DNA and introducing ends compatible with the linearized expression vector.

SEQ ID NO. 1:

Primer 1: 5′-WSN GAY AAY ATH CCN GGN GT-3′

SEQ ID NO. 2:

Primer 2: 5′-NCC NAC YTC NAC YTC NAR NGG-3′

SEQ ID NO. 3:

Primer 3: 5′-CAA TTC AGG GCA GTG CTG CTG ATA TC-3′

SEQ ID NO. 4:

Primer 4: 5′-GAG CTT CTG GGC ACT CTT TTC GCC-3′

SEQ ID NO. 5:

Primer 5: 5′-CGA ATT CGG CCG TCA TGA AAC TGG TTA TAT TCG ATG GAA ACA G-3′

SEQ ID NO. 6:

Primer 6: 5′-CGA ATT GGA TCC GTT TTG TCT CAT ACC AGT TCA GTC CTT C-3′

The gene is operably linked to appropriate control sequences for expression in either prokaryotic or eucaryotic host/vector systems. The vector preferably encodes all functions required for transformation and maintenance in a suitable host, and may encode selectable markers and/or control sequences for polymerase expression. Active recombinant thermostable polymerase can be produced by transformed host cultures either continuously or after induction of expression. Active thermostable polymerase can be recovered either from host cells or from the culture media if the protein is secreted through the cell membrane.

It is also preferable that Anaerocellum thermophilum thermostable polymerase expression is tightly controlled in E.coli during cloning and expression. Vectors useful in practicing the present invention should provide varying degrees of controlled expression of Anaerocellum thermophilum polymerase by providing some or all of the following control features: (1) promoters or sites of initiation of transcription, either directly adjacent to the start of the polymerase gene or as fusion proteins, (2) operators which could be used to turn gene expression on or off, (3) ribosome binding sites for improved translation, and (4) transcription or translation termination sites for improved stability. Appropriate vectors used in cloning and expression of Anaerocellum thermophilum polymerase include, for example, phage and plasmids. Example of phage include lambda gt11 (Promega), lambda Dash (Stratagene) lambda ZapII (Stratagene). Examples of plasmids include pBR322, pBTac2 (Boehringer Mannheim), pBluescript (Stratagene), pET3A (Rosenberg, A. H. et al., (1987) Gene 56:125-135), pASK75 (Biometra) and pET11C (Studier, F. W. et al. (1990) Methods in Enzymology, 185:60-89). According to the present invention the use of a plasmid has shown to be advantageously, particularly pASK75 (Biometra). The Plasmid pASK75 carrying the Anaerocellum thermophilum DNA polymerase gene is then designated pAR10.

Standard protocols exist for transformation, phage infection and cell culture (Maniatis, et al. (1982) Molecular Cloning: A Laboratory Manual, Cold Spring Harbour Laboratory Press). Of the numerous E. coli strains which can be used for plasmid transformation, the preferred strains include JM110 (ATCC 47013), LE392 pUBS 520 (Maniatis et al. supra; Brinkmann et al., (1989) Gene 85:109-114;), JM101 (ATCC No. 33876), XL1 (Stratagene), and RR1 (ATCC no. 31343), and BL21 (DE3) plysS (Studier, F. W. et al., (1990) Methods in Enzymology, supra). According to the present invention the use of the E. coli strain LE392 pUBS 520 has shown to be advantageously. The E. coli strain7221 LE392 pUBS 520 transformed with the plasmid pASK75 carrying the Anaerocellum thermophilum DNA polymerase gene (designated pAR10) is then designated E.coli AR220 (DSM No. 11177). E.coli strain XL1. Blue (Stratagene) is among the strains that can be used for lambda phage, and Y1089 can be used for lambda gt11 lysogeny. The transformed cells are preferably grown at 37° C. and expression of the cloned gene is induced with anhydrotetracycline.

Isolation of the recombinant DNA polymerase can be performed by standard techniques. Separation and purification of the DNA polymerase from the E.coli extract can be performed by standard methods. These methods include, for example, methods utilizing solubility such as salt precipitation and solvent precipitation, methods utilizing the difference in molecular weight such as dialysis, ultra-filtration, gel-filtration, and SDS-polyacrylamide gel electrophoresis, methods utilizing a difference in electric charge such as ion-exchange column chromatography, methods utilizing specific interaction such as affinity chromatography, methods utilizing a difference in hydrophobicity such as reversed-phase high performance liquid chromatography and methods utilizing a difference in isoelectric point such as isoelectric focussing electrophoresis.

The thermostable enzyme of this invention may be used for any purpose in which such enzyme activity is necessary or desired. In a particularly preferred embodiment, the enzyme catalyzes the nucleic acid amplification reaction known as PCR. This process for amplifying nucleic acid sequences is disclosed and claimed in EP 0 201 189. The PCR nucleic acid amplification method involves amplifying at least one specific nucleic acid sequence contained in a nucleic acid or a mixture of nucleic acids and produces double stranded DNA. Any nucleic acid sequence, in purified or nonpurified form, can be utilized as the starting nucleic acid(s), provided it contains or is suspected to contain the specific nucleic acid sequence desired. The nucleic acid to be amplified can be obtained from any source, for example, from plasmids such as pBR322, from cloned DNA or RNA, from natural DNA or RNA from any source, including bacteria, yeast, viruses, organelles, and higher organisms such as plants and animals, or from preparations of nucleic acids made in vitro. DNA or RNA may be extracted from blood, tissue material such as chorionic villi, or amniotic cells by a variety of techniques. See, e.g., Maniatis T. et al., 1982, Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.) pp. 280-281. Thus the process may employ, for example, DNA or RNA, including messenger RNA, which DNA or RNA may be single-stranded or double-stranded. In addition, a DNA-RNA hybrid which contains one strand of each may be utilized.

The amplification of target sequences in DNA or from RNA may be performed to proof the presence of a particular sequence in the sample of nucleic acid to be analyzed or to clone a specific gene. DNA polymerase from Anaerocellum thermophilum is very useful for these processes. Due to the fact that the DNA polymerase from Anaerocellum thermophilum requires Mg⁺⁺ ions as a cofactor instead of Mn⁺⁺ like the other DNA polymerases from thermophilic organisms with reverse transcriptase activity of the state of the art the RNA templates can be copied with higher fidelity. These properties make DNA polymerase from Anaerocellum thermophilum a very useful tool for the molecular biologist. DNA polymerase from Anaerocellum thermophilum may also be used to simplify and improve methods for detection of RNA target molecules in a sample. In these methods DNA polymerase from Anaerocellum thermophilum catalyzes: (a) reverse transcription, (b) second strand cDNA synthesis, and, if desired, (c) amplification by PCR. The use of DNA polymerase from Anaerocellum thermophilum in the described methods eliminates the previous requirement of two sets of incubation conditions which were necessary due to the use of different enzymes for each step. The use of DNA polymerase from Anaerocellum thermophilum provides RNA reverse transcription and amplification of the resulting complementary DNA with enhanced specificity and with fewer steps than previous RNA cloning and diagnostic methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a photograph of a DNA polymerase assay performed in situ. The DNA polymerase activity of DNA polymerase from Anaerocellum thermophilum is analysed in comparison with DNA polymerase I and Klenow fragment of E. coli and DNA polymerase from Thermus thermophilus. A fraction of DNA polymerase from Anaerocellum thermophilum was submitted to electrophoresis on a SDS-polyacrylamide gel containing activated (DNAseI treated) DNA. After electrophoresis the SDS was removed, the proteins were renatured over night and incubated at 72° C. in the presence of magnesium salt, dNTPs and digoxigenin labeled dUTPs to allow synthesis of the complementary strand. The nucleic acid was blotted to a nylon membrane and the newly synthesized DNA detected by a chemiluminescence reaction.

As control proteins DNA polymerase I and Klenow fragment of E.coli and DNA polymerase from Thermus thermophilus were analyzed on the same gel. Using these proteins as standards the apparent molecular weight of DNA polymerase from Anaerocellum thermophilum of 96.000 to 100.000 Daltons can be deduced.

FIG. 2 shows results obtained from assays determining the relative activity of the reverse transcriptase in dependence of varying concentrations of magnesium and manganese ions.

FIG. 3 shows the thermostability of DNA polymerase from Anaerocellum thermophilum. Aliquots of the DNA polymerase were incubated at 80° C. and the activity measured at the times indicated in the figure.

FIG. 4 shows the DNA sequence (SEQ ID NO: 7) of the polymerase gene of Anaerocellum thermophilum and the derived peptide sequence (SEQ ID NO: 8) for Anaerocellum thermophilum.

FIG. 5 shows the comparison ot the reverse transcriptase activity of Anaerocellum thermophilum polymerase with Thermus filiformis and Thermus thermophilus.

EXAMPLE 1 Isolation of DNA Polymerase

For recovering the native protein Anaerocellum thermophilum may be grown using any suitable technique, such as the technique described by Svetlichny et al., 1991, System. Appl. Microbiol. Vol. 14, p. 205-208. After cell growth one preferred method for isolation and purification of the enzyme is accomplished using the multi-step process as follows:

The cells are thawed, suspended in buffer A (40 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7 mM 2-mercaptoethanol, 0.4 M NaCl, 10 mM Pefabloc™ SC (4-(2-Aminoethyl)-benzolsulfonyl-fluorid, Hydrochlorid) and lysed by twofold passage through a Gaulin homogenizer. The raw extract is cleared by centrifgation, the supernatant dialyzed against buffer B (40 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7 mM 2-mercaptoethanol, 10% Glycerol) and applied onto a column filled with Heparin-Sepharose (Pharmacia). In each case the columns are equilibrated with the starting solvent and after application of the sample the columns are washed with the threefold of their volume with this solvent. Eluation of the first column is performed with a linear gradient of 0 to 0.5 M NaCl in Buffer B. The fractions showing polymerase activity are pooled and ammonium sulfate is added to a final concentration of 20%. This solution is applied to a hydrophobic column containing Butyl-TSK-Toyopearl (TosoHaas). This column is eluted with a falling gradient of 20 to 0% ammonium sulfate. The pool containing the activity is dialyzed and again transferred to a column of DEAE-Sepharose (Pharmacia) and eluted with a linear gradient of 0-0.5 M NaCl in buffer B. The fourth column contains Tris-Acryl-Blue (Biosepra) and is eluted as in the preceding case. Finally the active fractions are dialyzed against buffer C (20 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 7.0 mM 2-mercaptoethanol, 100 mM NaCl, 50% Glycerol).

EXAMPLE 2 Detection of Endonuclease, Exonuclease and Ribonuclease Activities

Absence of endonuclease activity: 1 μg of plasmid DNA is incubated for 4 hours with an excess of purified DNA polymerase in 50 μl of test buffer with a paraffin oil overlay at 72° C.

Absence of nonspecific exonuclease activity: 1 μg of EcoRI/HindIII-fragments of lambda DNA are incubated in 50 μl of test buffer in the absence and presence of dNTPs (1 mM final concentration each) with an excess of purified DNA polymerase for 4 hours at 72° C. with a paraffin overlay.

Absence of ribonuclease activity: 3 μg of MS2 RNA are incubated with an excess of DNA polymerase in 20 μl of test buffer for 4 hours at 72° C. The RNA is subsequently analyzed by electrophoresis in a MOPS gel (Maniatis et al., 1982, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor, N.Y.).

EXAMPLE 3 Determination of DNA Polymerase Activity

DNA polymerase activity was either measured by incorporation of ³²P-dCTP or by incorporation of digoxigenin labeled dUTP into the synthesized DNA.

Detection and quantification of ³²P-dCTP incorporation was measured as follows: The reaction mixture contained 50 mM Tris-HCl, pH 8.5; 12.5 mM (NH₄)₂SO₄; 10 mM KCl; 5 mM MgCl₂; 10 mM 2-mercaptoethanol, 200 μg/ml BSA, 200 μM of dATP, dGTP and dTTP, 100 μM dCTP, 12 μg of DNAse activated DNA from calf thymus and 0.1 μl of ³²P-dCTP (10 mCi/ml, 3000 Ci/mmol). After incubation for 30 min. at 70° C. the samples were placed on ice, 250 μl of 10% trichloroacetic acid were added, the samples mixed and incubated for 10 more min. on ice. 150 μl of the samples were filtrated through nylon membranes, the filters washed four times with 5% trichloroacetic acid. The filters were dried for 30 minutes at 80° C. and the radioactivity bound to the filters determined in a Packard Matrix 96 Direct Beta Counter.

Detection and quantification of the incorporated digoxigenin was performed essentially as described in Höltke, H.-J.; Sagner, G; Kessler, C. and Schmitz, G., 1992, Biotechniques Vol. 12, p. 104 -113. Typically, this assay is performed in a total volume of 50 μl of a reaction mixture composed of 1 or 2 μl of diluted (0.05 U-0.01 U) DNA polymerase and 50 mM Tris-HCl, pH 8.5; 12.5 mM (NH₄)₂SO₄; 10 mM KCl; 5 mM MgCl₂; 10 mM 2-mercaptoethanol; 33 μM dNTPs; 200 μg/ml BSA; 12 μg of DNAse activated DNA from calf thymus and 0.036 μM digoxigenin-dUTP.

The samples are incubated for 30 min. at 72° C., the reaction is stopped by addition of2 μl 0.5 M EDTA and the tubes placed on ice. After addition of 8 μl 5 M NaCl and 150 μl of Ethanol (precooled to −20° C.) the DNA is precipitated by incubation for 15 min. on ice and pelleted by centrifugation for 10 min. at 13000×rpm and 4° C. The pellet is washed with 100 μl of 70% Ethanol (precooled to −20° C.) and 0.2 M NaCl, centrifuged again and dried under vacuum. The pellets are dissolved in 50 μl Tris-EDTA (10 mM/0.1 mM; pH 7.5). 5 μl of the sample are spotted into a well of a nylon membrane bottomed white microwell plate (Pall Filtrationstechnik GmbH, Dreieich, FRG, product no: SM045BWP). The DNA is fixed to the membrane by baking for 10 min. at 70° C. The DNA loaded wells are filled with 100 μl of 0.45 μm-filtrated 1% blocking solution (100 mM maleic acid, 150 mM NaCl, 1% (w/v) casein, pH 7.5). All following incubation steps are done at room temperature. After incubation for 2 min. the solution is sucked through the membrane with a suitable vacuum manifold at −0.4 bar. After repeating the washing step, the wells are filled with 100 μl of a 1:10000-dilution anti-digoxigenin-AP, Fab fragments (Boehringer Mannheim, FRG, no: 1093274) diluted in the blocking solution described above. After incubation for 2 min. and sucking this step is repeated once. The wells are washed twice under vacuum with 200 μl of washing buffer 1 (100 mM maleic acid, 150 mM NaCl, 0.3%(v/v) Tween™ 20, pH 7.5). After washing another two times under vacuum with 200 μl washing buffer 2 (10 mM Tris-HCl, 100 mM NaCl, 50 mM MgCl₂, pH 9.5), 50 μl of CSPD™ (Boehringer Mannheim, no: 1655884) diluted 1:100 in washing buffer 2, which serves as a chemiluminescent substrate for the alkaline phosphatase, are added to the wells and the microwell plate is incubated for 5 min. at room temperature. The solution is then sucked through the membrane and after 10 min. fierier incubation at room temperature the RLU/s (Relative Light Unit per second) are detected in a Luminometer e.g. MicroLumat LB 96 P (EG&G Berthold, Wildbad, FRG).

With a serial dilution of Taq DNA polymerase a standard curve is prepared from which the linear range serves as a standard for the activity determination of the DNA polymerase to be analyzed.

EXAMPLE 4 Determination of Reverse Transcriptase Activity

Reverse transcriptase activity was measured using oligo dT primed poly A template by incorporation of either ³²P-dTTP or digoxigenin-labeled dUTP into the complementary strand. Incorporation of ³²P-dTTP was measured in a mixture containing 1 μg of poly A.(dT)₁₅, 500 μM of dTTP, 100 mg/ml BSA, 10 mM Tris-HCl, pH 8.5, 20 mM KCl, 0.5-10 mM MgCl₂ or 0.1-5 mM MnCl₂, 10 mM DTE, 0.5 μl of ³²P-dTTP (10 mM Ci/ml, 3000 Ci/mmol) and various amounts of DNA polymerase. The incubation temperature used was 50° C. The incorporated radioactivity was determined as described in the assay for determination of DNA polymerase activity.

Incorporation of digoxigenin-dUTP was measured in a mixture containing 1 μg of poly A.(dT)₁₅, 330 μM of dTTP, 0.36 μM of digoxigenin-dUTP, 200 mg/ml BSA, 10 mM Tris-HCl, pH 8.5, 20 mM KCl, 0.5-10 mM MgCl₂ or 0.1-5 mM MnCl₂, 10 mM DTE and various amounts of DNA polymerase. The incubation temperature used was 50° C. Detection of the radioactivity incorporated was performed in analogy to the procedure used for detection of DNA polymerase activity.

EXAMPLE 5 Detection of DNA Polymerase and Reverse Transcriptase Activity in situ

In situ PAGE analysis of polymerase activity and reverse transcriptase activity was performed essentially according to the method described by Spanos A. and Hübscher U., 1983, Methods in Enzymology Vol. 91 p. 263-277. Some minor, but essential modifications to the original method are, that the renaturation of the SDS-denatured polypeptides is performed in the presence of magnesium ions (3 mM) and DATP (0.5-1 μM) to assist refolding. In brief the method is as follows:

After separation of polypeptides from either crude cell extracts or purified samples on a denaturing 8% polyacrylamide gel (stacking gel 5% acrylamide) which contains 150 μg activated calf thymus DNA per ml gel volume, the gel is washed four times (15-30 min. each at room temperature with moderate shaking) in excess renaturation buffer (Tris-HCl, 50 mM, pH 8.4; EDTA, 1 mM; 2-mercaptoethanol, 3 mM; KCl, 50 mM; Glycerol, 5-10%) to remove SDS. Then the gel is incubated overnight in the same buffer, including 3 mM MgCl₂ and 0.5-1 μM DATP at 4° C. without agitation. The first four washes are repeated the next day with renaturation buffer. After the removal of SDS and renaturation of the proteins the gel is transferred into the reaction mixture consisting of Tris-HCl, 50 mM, pH 8.4; KCl, 50 mM, DTT, 3 mM; MgCl₂, 7 mM; 12 μM of DATP, dCTP, dGTP (each), 8 μM dTTP and 4 μM Dig-dUTP; 10% (v/v) glycerol. The gel is first incubated under shaking at room temperature (30 min.) and then slowly warmed up to 72° C. by temperature increments of 5° C. At each temperature interval DNA synthesis is allowed to proceed for 30 min., in order to detect also polymerase activity of mesophile control polymerases. After DNA synthesis, the DNA is transferred either electrophoretically (0.25×TBE) or by capillary blotting (15×SSC) to nylon membranes (Boehringer Mannheim) and UV crosslinked. Newly synthesized Dig-labeled DNA is detected according to the procedure described for analysis of DNA polymerase activity.

EXAMPLE 6 Cloning of the Anaerocellum thermophilum DNA Polymerase Gene

Preparation of chromosomal DNA from Anaerocellum thermophilum

0.8 g biomass of Anaerocellum thermophilum was suspended in 20 ml 1M KCl and centrifuged. Then the pellet was resuspended in 4.8 ml SET-buffer (150 mM NaCl, 15 mM EDTA, pH 8.0, 60 mM Tris-HCl, pH 8.0, 50 μg/μl RNaseA), after which 1 ml 20% SDS and 50 μl of proteinase K (10 mg/ml) were added. The mixture was kept at 37° C. for 45 min. After extraction with phenol and chloroform the DNA was precipitated with ethanol and dissolved in H₂O. Thus about 3.8 mg of DNA were obtained.

Amplification of specific DNA by PCR

For amplification of the gene encoding the DNA polymerase of Anaerocellum thermophilum by the PCR technique two mixed oligonucleotides (primer 1 and 2) were designed on the basis of conserved regions of family A DNA polymerases as published by Braithwaite D. K. and Ito J., 1993, Nucl. Acids Res. Vol. 21, p. 787-802.

SEQ ID NO. 1:

Primer 1: 5′-WSN GAY AAY ATH CCN GGN GT-3′

SEQ ID NO.2:

Primer 2: 5′-NCC NAC YTC NAC YTC NAR NGG-3′

The PCR amplification was performed in 100 μl buffer containing 750 ng of genomic DNA from Anaerocellum thermophilum, 10 mM Tris-HCl, pH 8.8, 2.5 mM MgCl₂, 50 mM KCl, 200 μM dNTPs, 100 pmoles of each primer and 2.5 units of Taq polymerase (Boehringer Mainheim GmbH). The target sequence was amplified by first denaturing at 95° C. for 2 min. followed by 30 cycles of 95° C. for 0.5 min, 50° C. for 1 min. and 72° C. for 2 min. Thermal cycling was performed in a Perkin Elmer GenAmp 9600 thermal cycler. Agarose gel electrophoresis showed, that a fragment of approximately 1,900 base pairs was amplified specifically. This fragment was ligated into the pCR™II vector (Invitrogen) and the sequence determined by cycle-sequencing. The amino acid sequence deduced from this nucleotide sequence was very similar to that of other known DNA polymerases, so that primer 3 and 4 could be designed for inverse PCR.

SEQ ID NO. 3:

Primer 3: 5′-CAA TTC AGG GCA GTG CTG CTG ATA TC-3′

SEQ ID NO.4:

Primer 4: 5′-GAG CTT CTG GGC ACT CTT TTC GCC-3′

Inverse PCR was performed essentially as described in Triglia T. et al., 1988, Nucleic Acids Research Vol. 16, p. 8186.5 μg genomic DNA from Anaerocellum thermophilum were cleaved by EcoRI according to supplier's specifications (Boehringer Mannheim GmbH) and treated with an equal volume of phenol/chloroform mixture. The aqueous phase was removed, the DNA precipitated with ethanol and collected by centrifuigation.

For circularization the digested DNA was diluted to a concentration of 50 ng/μl in ligation buffer (Boehringer Mannheim GmbH). The ligation reaction was initiated by the addition of T4 DNA Ligase (Boehringer Mannheim GmbH) to a concentration of 0.2 units/μl and the reaction was allowed to proceed for 15 hrs at 15° C. The ligated DNA was then precipitated with ethanol and collected by centrifugation.

The PCR was performed in 50 μl buffer containing 50 mM Tris-Cl, pH 9.2, 16 mM (NH₄)₂SO₄, 2.25 mM MgCl₂, 2% (v/v) DMSO, 0.1% (v/v) Tween™ 20 (Poly(oxyethylen)_(n)-sorbitan-mono-laurat), 700 ng of circularized DNA obtained as described above, 50 pmoles of each primer, 500 μM dNTP and 0.75 μl enzyme mix (Expand Long Template PCR System, Boehringer Mannheim GmbH).

The cycle conditions were as follows:

 1x denaturation of template for 2 min. at 92° C. denaturation at 92° C. for 10 sec. 10x annealing at 64° C. for 30 elongation at 68° C. for 2 min. denaturation at 92° C. for 10 sec. annealing at 64° C. for 30 sec. 20x elongation at 68° C. for 2 min. + cycle elongation of 20 sec. for each cycle

Agarose gel electrophoresis revealed a specifically amplified DNA fragment 6,500 base pairs long. The DNA fragment was ligated into the pCR™II vector (Invitrogen) and sequenced. Deduced from this sequence primer 5 and 6 coding for the 5′- and 3′-ends, respectively, of the polymerase region could be designed. Primer 5 contained a EclXI site and primer 6 contained a BamHI site. The PCR was performed under the same conditions as described above (inverse PCR) using 750 ng genomic DNA from Anaerocellum thermophilum as template.

SEQ ID NO. 5:

Primer 5: 5′-CGA ATT CGG CCG TCA TGA AAC TGG TTA TAT TCG ATG GAA ACA G-3′

SEQ ID NO. 6:

Primer 6: 5′-CGA ATT GGA TCC GTT TTG TCT CAT ACC AGT TCA GTC CTT C-3′

Cloning and Expression

The PCR product was purified by electrophoresis of 20 μl of the PCR mixture on a 0.8% agarose gel. The 2.552 kb band of the polymerase coding region was purified from the agarose by phenol extraction. The DNA was then treated with chloroform and precipitated with ethanol. The pellet was resuspended and digested with EclXI and BamHI according to supplier's specification (Boehringer Mannheim GmbH) to give cohesive ends for directional cloning. The DNA was ligated into the expression vector pASK75 (Biometra) that had also been digested with EclXI and BamHI. The ligated products were introduced into E.coli strain LE392 pUBS520 (Brinkmann U., et al., 1989, Gene Vol. 85, p. 109-114) by transformation. Transformants were grown on L-agar containing 100 μg/ml ampicillin and 50 μg/ml kanamycin to allow selection of recombinants. Colonies were picked and grown in L-broth containing 100 μg/ml ampicillin and 50 μg/ml kanamycin, and plasmid DNA was prepared by alkaline lysis. The plasmids were screened for insertions by digestion with BamHI. Those recombinants containing inserts were grown in L-broth containing ampicillin and kanamycin and tested for the expression of thermophilic DNA polymerase by induction of exponentially growing culture with 0.2 pg/ml anhydrotetracycline and assaying the heat-treated extracts for DNA polymerase activity as described above (determination of DNA polymerase activity). A recombinant expressing the DNA polymerase from Anaerocellum thermophilum was obtained. The strain was designated E.coli AR220 (DSM No. 11177) and the plasmid pAR10.

EXAMPLE 7

DNA polymerase from Anaerocellum thermophilum was compared with DNA polymerases from Thermus thermophilus and Thermus filiformis. Similar amounts (units) of the DNA polymerases were analyzed. Each enzyme was tested for DNA polymerase activity, for reverse transcriptase activity in the presence of Mg++ (5 mM) and reverse transcriptase activity in the presence of Mn++ (1 mM) under the reaction conditions optimal for the individual enzymes. In order to compare the ratio of DNA polymerase to reverse transcriptase activity, the relative light units (RLU) measured in the DNA polymerase assay were set to 100. The RLUs measured in the reverse transcriptase activity tests are expressed as percent of the polymerase activity. Results are shown in FIG. 5.

SEQUENCE LISTING <160> NUMBER OF SEQ ID NOS: 8 <210> SEQ ID NO 1 <211> LENGTH: 20 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <221> NAME/KEY: misc_feature <222> LOCATION: 3,15,18 <223> OTHER INFORMATION: n= a,t,c, or g <400> SEQUENCE: 1 wsngayaaya thccnggngt 20 <210> SEQ ID NO 2 <211> LENGTH: 21 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <221> NAME/KEY: misc_feature <222> LOCATION: 1,4,10,16,19 <223> OTHER INFORMATION: n= a,t,c, or g <400> SEQUENCE: 2 nccnacytcn acytcnarng g 21 <210> SEQ ID NO 3 <211> LENGTH: 26 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <400> SEQUENCE: 3 caattcaggg cagtgctgct gatatc 26 SEQ ID NO 4 <211> LENGTH: 24 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <400> SEQUENCE: 4 gagcttctgg gcactctttt cgcc 24 <210> SEQ ID NO 5 <211> LENGTH: 42 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <400> SEQUENCE: 5 cgaattcggc cgtcatgaaa ctggttatat tcgatggaaa ca 42 <210> SEQ ID NO 6 <211> LENGTH: 40 <212> TYPE: DNA <213> ORGANISM: Artificial Sequence <220> FEATURE: <223> OTHER INFORMATION: Description of Artificial Sequence: amplification primer <400> SEQUENCE: 6 cgaattggat ccgttttgtc tcataccagt tcagtcctcc 40 <210> SEQ ID NO 7 <211> LENGTH: 2553 <212> TYPE: DNA <213> ORGANISM: Anaerocellum thermophilum <220> FEATURE: <221> NAME/KEY: CDS <222> LOCATION: (1)..(2553) <223> OTHER INFORMATION: <400> SEQUENCE: 7 atg aaa ctg gtt ata ttc gat gga aac agc att ttg tac aga gcc ttt 48 Met Lys Leu Val Ile Phe Asp Gly Asn Ser Ile Leu Tyr Arg Ala Phe 1 5 10 15 ttt gct ctt cct gaa ctg aca acc tca aat aat att cca aca aac gct 96 Phe Ala Leu Pro Glu Leu Thr Thr Ser Asn Asn Ile Pro Thr Asn Ala 20 25 30 ata tat gga ttt gta aat gtg ata ttg aaa tat tta gaa caa gaa aaa 144 Ile Tyr Gly Phe Val Asn Val Ile Leu Lys Tyr Leu Glu Gln Glu Lys 35 40 45 cct gat tat gtt gct gta gca ttt gat aaa aga gga aga gag gca cga 192 Pro Asp Tyr Val Ala Val Ala Phe Asp Lys Arg Gly Arg Glu Ala Arg 50 55 60 aaa agc gag tac gaa gaa tat aaa gct aac aga aaa cct atg cca gat 240 Lys Ser Glu Tyr Glu Glu Tyr Lys Ala Asn Arg Lys Pro Met Pro Asp 65 70 75 80 aac ctt caa gta caa atc cct tat gtt cga gag att ctt tat gcc ttt 288 Asn Leu Gln Val Gln Ile Pro Tyr Val Arg Glu Ile Leu Tyr Ala Phe 85 90 95 aac att cca ata att gag ttt gaa gga tat gaa gca gat gat gta atc 336 Asn Ile Pro Ile Ile Glu Phe Glu Gly Tyr Glu Ala Asp Asp Val Ile 100 105 110 ggt tca ctt gtt aac cag ttc aaa aat act ggt ttg gat att gtt att 384 Gly Ser Leu Val Asn Gln Phe Lys Asn Thr Gly Leu Asp Ile Val Ile 115 120 125 att acg ggt gac agg gat act ctt cag ttg ctc gac aaa aat gta gtt 432 Ile Thr Gly Asp Arg Asp Thr Leu Gln Leu Leu Asp Lys Asn Val Val 130 135 140 gtg aag att gtt tca aca aaa ttt gat aaa aca gta gaa gat ttg tac 480 Val Lys Ile Val Ser Thr Lys Phe Asp Lys Thr Val Glu Asp Leu Tyr 145 150 155 160 act gtg gaa aat gtt aaa gaa aaa tat ggg gtt tgg gca aat caa gtg 528 Thr Val Glu Asn Val Lys Glu Lys Tyr Gly Val Trp Ala Asn Gln Val 165 170 175 cct gat tac aaa gcg ctt gtt gga gac caa tca gat aac att ccc ggg 576 Pro Asp Tyr Lys Ala Leu Val Gly Asp Gln Ser Asp Asn Ile Pro Gly 180 185 190 gta aag gga att ggc gaa aag agt gcc cag aag ctc ttg gaa gag tac 624 Val Lys Gly Ile Gly Glu Lys Ser Ala Gln Lys Leu Leu Glu Glu Tyr 195 200 205 tca tcc tta gaa gag ata tac caa aat tta gat aaa att aaa agt tcc 672 Ser Ser Leu Glu Glu Ile Tyr Gln Asn Leu Asp Lys Ile Lys Ser Ser 210 215 220 att cgt gaa aag tta gaa gca gga aaa gat atg gcg ttt tta tcc aag 720 Ile Arg Glu Lys Leu Glu Ala Gly Lys Asp Met Ala Phe Leu Ser Lys 225 230 235 240 cgc tta gca aca att gta tgt gat tta cca cta aat gtt aaa ctt gaa 768 Arg Leu Ala Thr Ile Val Cys Asp Leu Pro Leu Asn Val Lys Leu Glu 245 250 255 gac cta aga aca aaa gag tgg aac aag gaa agg ctc tat gag att ttg 816 Asp Leu Arg Thr Lys Glu Trp Asn Lys Glu Arg Leu Tyr Glu Ile Leu 260 265 270 gtg cag tta gag ttc aaa agc ata ata aaa cgg tta gga gtt cta tca 864 Val Gln Leu Glu Phe Lys Ser Ile Ile Lys Arg Leu Gly Val Leu Ser 275 280 285 gaa gtt caa ttt gaa ttt gtt cag cag cga acc gat ata cct gac gtt 912 Glu Val Gln Phe Glu Phe Val Gln Gln Arg Thr Asp Ile Pro Asp Val 290 295 300 gaa caa aaa gag ctt gaa agt att tca caa ata aga tca aaa gag att 960 Glu Gln Lys Glu Leu Glu Ser Ile Ser Gln Ile Arg Ser Lys Glu Ile 305 310 315 320 cca tta atg ttt gta cag ggc gaa aaa tgt ttt tat tta tat gat caa 1008 Pro Leu Met Phe Val Gln Gly Glu Lys Cys Phe Tyr Leu Tyr Asp Gln 325 330 335 gaa agt aat act gta ttt ata aca agt aat aaa ctt ttg ata gag gag 1056 Glu Ser Asn Thr Val Phe Ile Thr Ser Asn Lys Leu Leu Ile Glu Glu 340 345 350 att tta aaa agt gat act gtg aaa att atg tat gat ttg aaa aat ata 1104 Ile Leu Lys Ser Asp Thr Val Lys Ile Met Tyr Asp Leu Lys Asn Ile 355 360 365 ttt cat caa ctc aac ctg gaa gac act aat aat att aaa aat tgc gaa 1152 Phe His Gln Leu Asn Leu Glu Asp Thr Asn Asn Ile Lys Asn Cys Glu 370 375 380 gat gta atg att gct tcc tat gtt ctt gac agc aca aga agt tca tat 1200 Asp Val Met Ile Ala Ser Tyr Val Leu Asp Ser Thr Arg Ser Ser Tyr 385 390 395 400 gag tta gaa acg ttg ttt gta tct tac ttg aac act gac ata gaa gct 1248 Glu Leu Glu Thr Leu Phe Val Ser Tyr Leu Asn Thr Asp Ile Glu Ala 405 410 415 gta aaa aaa gac aag aag ata gtc tct gtg gta ctt cta aaa cgg tta 1296 Val Lys Lys Asp Lys Lys Ile Val Ser Val Val Leu Leu Lys Arg Leu 420 425 430 tgg gac gag ctt ttg aga tta ata gat tta aat tca tgc cag ttt tta 1344 Trp Asp Glu Leu Leu Arg Leu Ile Asp Leu Asn Ser Cys Gln Phe Leu 435 440 445 tat gag aat ata gaa aga cct ctt atc cca gtt cta tat gaa atg gaa 1392 Tyr Glu Asn Ile Glu Arg Pro Leu Ile Pro Val Leu Tyr Glu Met Glu 450 455 460 aaa aca gga ttt aag gtg gat aga gat gcc ctc atc caa tat acc aaa 1440 Lys Thr Gly Phe Lys Val Asp Arg Asp Ala Leu Ile Gln Tyr Thr Lys 465 470 475 480 gag att gaa aac aaa ata tta aaa ctt gaa acg cag ata tac cag att 1488 Glu Ile Glu Asn Lys Ile Leu Lys Leu Glu Thr Gln Ile Tyr Gln Ile 485 490 495 gca ggt gag tgg ttt aac ata aat tca ccg aaa cag ctt tct tac att 1536 Ala Gly Glu Trp Phe Asn Ile Asn Ser Pro Lys Gln Leu Ser Tyr Ile 500 505 510 ttg ttt gaa aag cta aaa ctt cct gta ata aag aag aca aaa aca gga 1584 Leu Phe Glu Lys Leu Lys Leu Pro Val Ile Lys Lys Thr Lys Thr Gly 515 520 525 tat tcc act gat gcc gag gtt tta gaa gag ctt ttt gac aaa cat gaa 1632 Tyr Ser Thr Asp Ala Glu Val Leu Glu Glu Leu Phe Asp Lys His Glu 530 535 540 ata gtt cct ctt att ttg gat tac agg atg tat aca aag ata ctg aca 1680 Ile Val Pro Leu Ile Leu Asp Tyr Arg Met Tyr Thr Lys Ile Leu Thr 545 550 555 560 act tac tgt cag gga tta cta cag gca ata aat cct tct tcg ggt aga 1728 Thr Tyr Cys Gln Gly Leu Leu Gln Ala Ile Asn Pro Ser Ser Gly Arg 565 570 575 gtt cat aca acc ttt atc caa aca ggt aca gcc aca gga aga ctt gca 1776 Val His Thr Thr Phe Ile Gln Thr Gly Thr Ala Thr Gly Arg Leu Ala 580 585 590 agc agc gat cct aat tta caa aat ata cct gta aaa tat gat gag ggg 1824 Ser Ser Asp Pro Asn Leu Gln Asn Ile Pro Val Lys Tyr Asp Glu Gly 595 600 605 aaa ttg ata cga aag gtt ttt gta cct gag ggt gga cat gta ctg att 1872 Lys Leu Ile Arg Lys Val Phe Val Pro Glu Gly Gly His Val Leu Ile 610 615 620 gat gca gat tat tcc caa att gag ctg aga ata ctt gcc cat att tct 1920 Asp Ala Asp Tyr Ser Gln Ile Glu Leu Arg Ile Leu Ala His Ile Ser 625 630 635 640 gaa gat gaa aga ctt ata agt gct ttc aaa aat aat gtt gac att cat 1968 Glu Asp Glu Arg Leu Ile Ser Ala Phe Lys Asn Asn Val Asp Ile His 645 650 655 tcg cag aca gca gct gag gtt ttt ggt gta gac ata gcc gat gtt act 2016 Ser Gln Thr Ala Ala Glu Val Phe Gly Val Asp Ile Ala Asp Val Thr 660 665 670 cca gag atg aga agt caa gct aaa gca gta aat ttt ggt ata gtt tat 2064 Pro Glu Met Arg Ser Gln Ala Lys Ala Val Asn Phe Gly Ile Val Tyr 675 680 685 ggg att tct gat tat ggt ctt gca agg gat att aaa att tcc agg aaa 2112 Gly Ile Ser Asp Tyr Gly Leu Ala Arg Asp Ile Lys Ile Ser Arg Lys 690 695 700 gaa gct gca gag ttt ata aat aag tat ttt gag cgt tat ccc aaa gtt 2160 Glu Ala Ala Glu Phe Ile Asn Lys Tyr Phe Glu Arg Tyr Pro Lys Val 705 710 715 720 aaa gag tat tta gat aat act gtt aag ttt gct cgt gat aat gga ttt 2208 Lys Glu Tyr Leu Asp Asn Thr Val Lys Phe Ala Arg Asp Asn Gly Phe 725 730 735 gtt ttg act tta ttt aat aga aag aga tat ata aaa gac ata aaa tct 2256 Val Leu Thr Leu Phe Asn Arg Lys Arg Tyr Ile Lys Asp Ile Lys Ser 740 745 750 aca aac aga aac tta agg ggt tat gca gaa agg att gca atg aat tcg 2304 Thr Asn Arg Asn Leu Arg Gly Tyr Ala Glu Arg Ile Ala Met Asn Ser 755 760 765 cca att cag ggc agt gct gct gat atc atg aaa ttg gca atg att aag 2352 Pro Ile Gln Gly Ser Ala Ala Asp Ile Met Lys Leu Ala Met Ile Lys 770 775 780 gtt tat cag aaa ctt aaa gaa aac aat ctc aaa tca aaa ata att ttg 2400 Val Tyr Gln Lys Leu Lys Glu Asn Asn Leu Lys Ser Lys Ile Ile Leu 785 790 795 800 cag gta cac gat gag ctt tta att gaa gcc cca tac gaa gaa aag gat 2448 Gln Val His Asp Glu Leu Leu Ile Glu Ala Pro Tyr Glu Glu Lys Asp 805 810 815 ata gta aag gaa ata gta aaa aga gaa atg gaa aat gcg gta gct tta 2496 Ile Val Lys Glu Ile Val Lys Arg Glu Met Glu Asn Ala Val Ala Leu 820 825 830 aaa gta cct ttg gta gtt gaa gtg aaa gaa gga ctg aac tgg tat gag 2544 Lys Val Pro Leu Val Val Glu Val Lys Glu Gly Leu Asn Trp Tyr Glu 835 840 845 aca aaa tag 2553 Thr Lys 850 <210> SEQ ID NO 8 <211> LENGTH: 850 <212> TYPE: PRT <213> ORGANISM: Abedus herberti <400> SEQUENCE: 8 Met Lys Leu Val Ile Phe Asp Gly Asn Ser Ile Leu Tyr Arg Ala Phe 1 5 10 15 Phe Ala Leu Pro Glu Leu Thr Thr Ser Asn Asn Ile Pro Thr Asn Ala 20 25 30 Ile Tyr Gly Phe Val Asn Val Ile Leu Lys Tyr Leu Glu Gln Glu Lys 35 40 45 Pro Asp Tyr Val Ala Val Ala Phe Asp Lys Arg Gly Arg Glu Ala Arg 50 55 60 Lys Ser Glu Tyr Glu Glu Tyr Lys Ala Asn Arg Lys Pro Met Pro Asp 65 70 75 80 Asn Leu Gln Val Gln Ile Pro Tyr Val Arg Glu Ile Leu Tyr Ala Phe 85 90 95 Asn Ile Pro Ile Ile Glu Phe Glu Gly Tyr Glu Ala Asp Asp Val Ile 100 105 110 Gly Ser Leu Val Asn Gln Phe Lys Asn Thr Gly Leu Asp Ile Val Ile 115 120 125 Ile Thr Gly Asp Arg Asp Thr Leu Gln Leu Leu Asp Lys Asn Val Val 130 135 140 Val Lys Ile Val Ser Thr Lys Phe Asp Lys Thr Val Glu Asp Leu Tyr 145 150 155 160 Thr Val Glu Asn Val Lys Glu Lys Tyr Gly Val Trp Ala Asn Gln Val 165 170 175 Pro Asp Tyr Lys Ala Leu Val Gly Asp Gln Ser Asp Asn Ile Pro Gly 180 185 190 Val Lys Gly Ile Gly Glu Lys Ser Ala Gln Lys Leu Leu Glu Glu Tyr 195 200 205 Ser Ser Leu Glu Glu Ile Tyr Gln Asn Leu Asp Lys Ile Lys Ser Ser 210 215 220 Ile Arg Glu Lys Leu Glu Ala Gly Lys Asp Met Ala Phe Leu Ser Lys 225 230 235 240 Arg Leu Ala Thr Ile Val Cys Asp Leu Pro Leu Asn Val Lys Leu Glu 245 250 255 Asp Leu Arg Thr Lys Glu Trp Asn Lys Glu Arg Leu Tyr Glu Ile Leu 260 265 270 Val Gln Leu Glu Phe Lys Ser Ile Ile Lys Arg Leu Gly Val Leu Ser 275 280 285 Glu Val Gln Phe Glu Phe Val Gln Gln Arg Thr Asp Ile Pro Asp Val 290 295 300 Glu Gln Lys Glu Leu Glu Ser Ile Ser Gln Ile Arg Ser Lys Glu Ile 305 310 315 320 Pro Leu Met Phe Val Gln Gly Glu Lys Cys Phe Tyr Leu Tyr Asp Gln 325 330 335 Glu Ser Asn Thr Val Phe Ile Thr Ser Asn Lys Leu Leu Ile Glu Glu 340 345 350 Ile Leu Lys Ser Asp Thr Val Lys Ile Met Tyr Asp Leu Lys Asn Ile 355 360 365 Phe His Gln Leu Asn Leu Glu Asp Thr Asn Asn Ile Lys Asn Cys Glu 370 375 380 Asp Val Met Ile Ala Ser Tyr Val Leu Asp Ser Thr Arg Ser Ser Tyr 385 390 395 400 Glu Leu Glu Thr Leu Phe Val Ser Tyr Leu Asn Thr Asp Ile Glu Ala 405 410 415 Val Lys Lys Asp Lys Lys Ile Val Ser Val Val Leu Leu Lys Arg Leu 420 425 430 Trp Asp Glu Leu Leu Arg Leu Ile Asp Leu Asn Ser Cys Gln Phe Leu 435 440 445 Tyr Glu Asn Ile Glu Arg Pro Leu Ile Pro Val Leu Tyr Glu Met Glu 450 455 460 Lys Thr Gly Phe Lys Val Asp Arg Asp Ala Leu Ile Gln Tyr Thr Lys 465 470 475 480 Glu Ile Glu Asn Lys Ile Leu Lys Leu Glu Thr Gln Ile Tyr Gln Ile 485 490 495 Ala Gly Glu Trp Phe Asn Ile Asn Ser Pro Lys Gln Leu Ser Tyr Ile 500 505 510 Leu Phe Glu Lys Leu Lys Leu Pro Val Ile Lys Lys Thr Lys Thr Gly 515 520 525 Tyr Ser Thr Asp Ala Glu Val Leu Glu Glu Leu Phe Asp Lys His Glu 530 535 540 Ile Val Pro Leu Ile Leu Asp Tyr Arg Met Tyr Thr Lys Ile Leu Thr 545 550 555 560 Thr Tyr Cys Gln Gly Leu Leu Gln Ala Ile Asn Pro Ser Ser Gly Arg 565 570 575 Val His Thr Thr Phe Ile Gln Thr Gly Thr Ala Thr Gly Arg Leu Ala 580 585 590 Ser Ser Asp Pro Asn Leu Gln Asn Ile Pro Val Lys Tyr Asp Glu Gly 595 600 605 Lys Leu Ile Arg Lys Val Phe Val Pro Glu Gly Gly His Val Leu Ile 610 615 620 Asp Ala Asp Tyr Ser Gln Ile Glu Leu Arg Ile Leu Ala His Ile Ser 625 630 635 640 Glu Asp Glu Arg Leu Ile Ser Ala Phe Lys Asn Asn Val Asp Ile His 645 650 655 Ser Gln Thr Ala Ala Glu Val Phe Gly Val Asp Ile Ala Asp Val Thr 660 665 670 Pro Glu Met Arg Ser Gln Ala Lys Ala Val Asn Phe Gly Ile Val Tyr 675 680 685 Gly Ile Ser Asp Tyr Gly Leu Ala Arg Asp Ile Lys Ile Ser Arg Lys 690 695 700 Glu Ala Ala Glu Phe Ile Asn Lys Tyr Phe Glu Arg Tyr Pro Lys Val 705 710 715 720 Lys Glu Tyr Leu Asp Asn Thr Val Lys Phe Ala Arg Asp Asn Gly Phe 725 730 735 Val Leu Thr Leu Phe Asn Arg Lys Arg Tyr Ile Lys Asp Ile Lys Ser 740 745 750 Thr Asn Arg Asn Leu Arg Gly Tyr Ala Glu Arg Ile Ala Met Asn Ser 755 760 765 Pro Ile Gln Gly Ser Ala Ala Asp Ile Met Lys Leu Ala Met Ile Lys 770 775 780 Val Tyr Gln Lys Leu Lys Glu Asn Asn Leu Lys Ser Lys Ile Ile Leu 785 790 795 800 Gln Val His Asp Glu Leu Leu Ile Glu Ala Pro Tyr Glu Glu Lys Asp 805 810 815 Ile Val Lys Glu Ile Val Lys Arg Glu Met Glu Asn Ala Val Ala Leu 820 825 830 Lys Val Pro Leu Val Val Glu Val Lys Glu Gly Leu Asn Trp Tyr Glu 835 840 845 Thr Lys 850 

We claim:
 1. An isolated polypeptide encoded by SEQ ID NO:7.
 2. The polypeptide of claim 1 which has an apparent molecular weight between about 96,000 to about 100,000 daltons.
 3. A process for the preparation of the polypeptide of claim 1 comprising the steps of: a. culturing a cell comprising SEQ ID NO:7; and b. isolating the polypeptide from the cell. 